Also, see Word2MediaWikiPlus, an extension to Word, that is promising, but not yet ready for primetime.

Wikitext Converters

PHP

Perhaps the best choice from a PHP developers point of view is the Text_Wiki PEAR Package. It "transforms Wiki and BBCode markup into XHTML, LaTeX or plain text markup." It has even a adapter for Mediawiki code

Word Cleaners

Word-to-HTML works for files up to 20 KB; subscription needed for larger files or frequent use

The Clean MS Word HTML Page open source project does much the same thing; paste in Word content, click the Clean button, then get your purified HTML that you can paste into the raw HTML tab of your blog post editor